VISCOSITY INDEX IMPROVER, LUBRICANT OIL ADDITIVE, AND LUBRICANT OIL COMPOSITION

摘要

A viscosity index improver of the present invention contains a star polymer obtained by a reaction of divinylbenzene with alkyl methacrylate containing stearyl methacrylate, the star polymer having a core part and an arm part, wherein the core part is derived from the divinylbenzene and the ann part is a polymer chain of the alkyl methacrylate. A lubricant oil additive and a lubricant oil composition of the present invention contain the above viscosity index improver.